/**
 * ZIP file creation utility for ComfyUI Viewer
 * Creates ZIP blobs without external dependencies
 */

/**
 * Create a ZIP blob from an array of files
 * @param {Array<{name: string, content: string}>} files - Files to include
 * @returns {Promise<Blob>} ZIP blob
 */
export async function createZipBlob(files) {
  const crc32 = (data) => {
    let crc = 0xFFFFFFFF;
    const table = new Uint32Array(256);
    for (let i = 0; i < 256; i++) {
      let c = i;
      for (let j = 0; j < 8; j++) c = (c & 1) ? (0xEDB88320 ^ (c >>> 1)) : (c >>> 1);
      table[i] = c;
    }
    for (let i = 0; i < data.length; i++) crc = table[(crc ^ data[i]) & 0xFF] ^ (crc >>> 8);
    return (crc ^ 0xFFFFFFFF) >>> 0;
  };

  const encoder = new TextEncoder();
  const parts = [];
  const centralDir = [];
  let offset = 0;

  for (const file of files) {
    const nameBytes = encoder.encode(file.name);
    const contentBytes = encoder.encode(file.content);
    const crc = crc32(contentBytes);
    const localHeader = new Uint8Array(30 + nameBytes.length);
    const view = new DataView(localHeader.buffer);
    
    view.setUint32(0, 0x04034B50, true);
    view.setUint16(4, 20, true);
    view.setUint16(6, 0, true);
    view.setUint16(8, 0, true);
    view.setUint16(10, 0, true);
    view.setUint16(12, 0, true);
    view.setUint32(14, crc, true);
    view.setUint32(18, contentBytes.length, true);
    view.setUint32(22, contentBytes.length, true);
    view.setUint16(26, nameBytes.length, true);
    view.setUint16(28, 0, true);
    localHeader.set(nameBytes, 30);

    const centralEntry = new Uint8Array(46 + nameBytes.length);
    const cView = new DataView(centralEntry.buffer);
    cView.setUint32(0, 0x02014B50, true);
    cView.setUint16(4, 20, true);
    cView.setUint16(6, 20, true);
    cView.setUint16(8, 0, true);
    cView.setUint16(10, 0, true);
    cView.setUint16(12, 0, true);
    cView.setUint16(14, 0, true);
    cView.setUint32(16, crc, true);
    cView.setUint32(20, contentBytes.length, true);
    cView.setUint32(24, contentBytes.length, true);
    cView.setUint16(28, nameBytes.length, true);
    cView.setUint16(30, 0, true);
    cView.setUint16(32, 0, true);
    cView.setUint16(34, 0, true);
    cView.setUint16(36, 0, true);
    cView.setUint32(38, 0, true);
    cView.setUint32(42, offset, true);
    centralEntry.set(nameBytes, 46);

    parts.push(localHeader, contentBytes);
    centralDir.push(centralEntry);
    offset += localHeader.length + contentBytes.length;
  }

  const centralDirOffset = offset;
  let centralDirSize = 0;
  for (const entry of centralDir) {
    parts.push(entry);
    centralDirSize += entry.length;
  }

  const endRecord = new Uint8Array(22);
  const endView = new DataView(endRecord.buffer);
  endView.setUint32(0, 0x06054B50, true);
  endView.setUint16(4, 0, true);
  endView.setUint16(6, 0, true);
  endView.setUint16(8, files.length, true);
  endView.setUint16(10, files.length, true);
  endView.setUint32(12, centralDirSize, true);
  endView.setUint32(16, centralDirOffset, true);
  endView.setUint16(20, 0, true);
  parts.push(endRecord);

  return new Blob(parts, { type: "application/zip" });
}